1. Field of the Invention
The present invention relates to a lubricating structure in an OHC internal combustion engine and, more specifically, to a lubricating structure with respect to the periphery of a valve stem.
2. Description of Background Art
In the OHC (Over Head Camshaft) type internal combustion engine provided with a camshaft on a cylinder head above a combustion chamber, pressure oil is supplied to a valve system of the camshaft or the valve stem located above by an oil pump driven by the operation of the internal combustion engine.
In the related art, lubricant for the valve stem is guided to the upper end of the valve stem from an oil path formed in a rocker arm. However, since the rocker arm, being relatively complex in structure, is a pivoting member, there arises a problem in that forming the oil path therein makes the structure further complex, and thus results in increase in production cost.
Accordingly, a method of guiding lubricant to the upper end of the valve stem through a lubricant guide attached to a camshaft holder is proposed (For example, see Patent document JP-UM-B-62-11294).
In JP-UM-B-62-11294, a structure in which the separate lubricant guide and the camshaft holder are secured together by two mounting bolts of the camshaft holder is disclosed.
Mounting bolt holes which the mounting bolts of the camshaft holder pass through are used as lubricant paths, and lubricant guided from the lubricant paths through an oil groove and an oil feed hole to the upper surface of the lubricant guide and accumulated is guided by the lubricant guide and supplied to the upper end of the valve stem.
In the construction described above, since the lubricant guide which is separate from the camshaft holder is secured together with the camshaft holder with the mounting bolt, the number of components increases and the assemblability is lowered and hence the cost is increased.